Quiet1:
While I carry my R9 exclusively in the pocket, I have an adjustable K&D Paddle Defender holster for my HKP7. I'll therefore presume to add my comments regarding the design of such a holster. In the order of your questions:
1. The paddle does secure the holster well and tightly against the body. It is more bulky than an IWB rig, but for me it is a lot more comfortable.
2. My K&D rig has a set of screws which allow the holster to be configured in a stong-side (I am right handed) "FBI forward cant," in a stong-side vertical position, or in the opposite cant for use as a weak-side cross-draw rig. In fact, I wanted the adjustable paddle primarily for use as a cross-draw rig for long trips in an automobile.
Here is a photograph of my K&D Paddle Defender with the P7 in the vertical configuration:
(http://i2.photobucket.com/albums/y30/RichardS/hkp7withmicartagripsandkdpaddledefe.jpg)